Air hammer construction



May 5, 1953 P. R. VAN SITTERT AIR HAMMER CONSTRUCTION 2 SHEETSSHEET 1 Filed March 10, 1950 aa 0 m 2 H r m W o v w II //4 h m e r 4 T 2 I mm lllllll n l Ill 7 FIG.

FIG.

IN VEN TOR.

- PAUL M y 5, 1953 P. R VAN SITTERT 2,637,300

AIR HAMMER CONSTRUCTION Filed March 10, 1950 2 SHEETS-SHEET 2 INVENTOR.

9 PAUL R. VAN SITTERT WMJZ aw/ Patented May 5, 1953 Paul R.v Van: Sittert; Shaker Heights; Ohio,-

signor to The Rotor- Tool Company, acorpora tion Of UhiO- Application March 10, 1950; Serial No. 148,990

3- Claims;

This invention relates to automatic directional valvin for a; reciprocatingfluid driven tool.

An object of this invention is to provide atool:

having a maximum cylinder'bcre'length.

Another object of this invention is to provide a pressure responsive fluid directing valve having flat surface contact valving; parts.

A still further object of this invention is to provide anannular valve-adapted to'constitute a portion of the cylinder bore of a fluid motor, the valve having flat v-alving surfaces easily replace ablein the eventof' damage or wear;

Other objects and-aaiuller understanding of the invention may behadbyrreferring to the following description and claims, taken in conjunction with the accompanying drawing-sin which:

Figure l is a longitudinal sectional view or" a pneumatic hammer employing; the principles of this invention; the section being taken along line l--lof Figure-3- and illustrates the piston in the striking position and thevalving parts moved to direct air toreturn the piston;

Figure 2 is a section similar to Figure 1 and illustrates. the piston in its: endwise wort: stroke with the valving parts positionedtodrive the pistonin its work stroke;

Figure 3 is a sectionalview along the line 3'--3 of Figure 1;

Figure 4 is a top view of the valve cap;

Figurefii is a sectional view along the line 5---5 The tool chosento. illustrate the principles of.

this invention is a pneumatic chipping hammer havingla toolbody. it with allongitudinal bore l I. A handle 12' having a hand grip portion Band a cap portionii'is threedablyv securedto the end.

of the body it; An airline I5 is adaptedt'o'supply the motive fluid to the. tool to reciprocably drive a piston It within the bore Iii. For the purposes of illustrating thisvtooL'a toolbit i-l is illustrated'as theimplement being hammeredby the piston it. A bushing I8 is mounted in the end of the body it to hold the tool/bit FL Air conduits likone of; which iSilIl view in'Figures i and: 2; extend longitudinally within the body l0 and serve to deliver. air to. the" end .of the: bore H near the tool bit ll. An air exhaust. 2fisisprovidedi atta: position between the ends of the bore Hi. to allow the motive fluid -to: escape from the bore? 11;.

An improved directing valve 21 i s-positioned at the end of. the bore it! opposite from the. tool: bit lzl and-is heldtirr pla'ceby the cap portion it of thehandle 12; as illustrated; in the Figures 1 and 2.. The directihgvalve tl is annularin: this embodiment and has aninternalbore 2'! of the same diameter as the bore: it; The: bore 2'? forms a continuation of the bore H, and the combined lengths of the bores H and"?! define-a tool cylinder 28. The piston Hi is adapted to reciprocate in the tool cylinder 2 B employing; both the bore Ii and the: bore 21. Therefore; the first advantageof the directing valve 2|- becomes apparent.

The directing valve 21-. serves as a useful portion.

ber 22 completely around. the external diameter of the valve 2-! Thus, the motive fluid may be delivered by the air line 1-5 intothe distributing chamber 22 surrounding the valve 2 i. The valve 2t then serves to direct the motive fluid to drive the-piston 16.

Referring to Figures 5 and 8, the directing valve- 2-! preferably comprises a: valve body 23 and-a valvecapZB inthisembodiment. An annular'groove 24- in the valve body, 23 and a flat wall sur-faoe 29 onthe valve cap'25 coop rate to define a valve chamber 2-6, as indicated in the Figures 1- and 2. The annular groove 24 is provided with a flat Wall bottom surface 30. The combination of thevalve body 23 and the valve capZEl-is preferably spokenotas a valve cage. A sleeve 38 serves to assure correct alignment of the body 23and the capiii, andprovides a smooth internaLborelltOmatch the internal bore H. A ring valve is-provided to reside within the valve chamber 26. The ring valve 35 has a flat surface 36- and a flat surface 3 and is dimensioned to fit freely: inthe valve'chamber 26 in'order that it. maybe moved'in tight-contact with the-flat wall 2 8a or the? flatzwall 30'.

Thevalve can 25 h: provided with at least one air entrance 3|, as best illustrated in Figure 5, but preferably has a plurality of air entrances 3| as illustrated in Figure 4. Thus, the volume of air which may enter into the valve chamber 23 may be relatively large without the necessity of providing one large entrance. In other Words, the plurality of air entrances 3! may be spoken of as an air fluid entrance'or fluid entrance means, it being understood that the number of entrances are multiplied strictly for design purposes. The cap 25 is also provided with an air exit 33 as illustrated in the Figure 5, or more properly, with air exit means. See Figure 4. Therefore, air entrance 3i, the chamber 26, and the air exit 33 define a fiuid passage from the distributing chamber 22 to the end of the tool cylinder 23. This passage may be followed by the arrows in Figure 2.

The valve body 23 is also provided with at least one air entrance 32, as illustrated in Figure 8, but preferably with a plurality of entrances, as illustrated in Figure 7. As discussed in connection with air entrances 3!, the air entrances 32 may be referred to as air entrance means. The valve body 23 is also provided with an air exit or exit means 34. Entrances 32, chamber 26, and air exit 34, therefore, define afiuid passage from the distributing chamber 22 to the air conduit 19 leading to .the tool cylinder 28. This pass-age may be followed by the arrows in Figure l. Pins 4| interlock the valve body 23 relative to the tool body H] to maintain alignment between air exit 34 and conduit I9.

The operation of the distributing valve 2! is set forth in the Figures 1 and 2. in what position the piston It happens to be as motive fluid is first applied to the tool, but for the purposes of illustration, let it be assumed that the piston i3 is in the position illustrated in the Figure 1. As the air is applied through the air line E5, the distributing chamber 22 is filled and air begins to enter through both the air entrances 3| and 32. The ring valve 35 will not stop air from entering both entrances during the initial starting moment. However, air-attempting to pass through the air conduits I!) to exhaust 20 will be blocked by the piston 16. On the other hand, air exhausting from the valve chamber 23 through the air exit 33 will be vented directly to atmosphere through the cylinder 23 and the exhaust 23. Therefore, a differential of air pressure is immediately built up between the two exits 33 and 34 from the valve 2! and the air will attempt to fiow out of the air exit 33. Thus, a differential of pressure is created between the flat surface 3'! and the flat surface 36 on the ring valve 35. The ring valve 35 is consequently drawn tightly against the fiat surface 29 of'the cap 25 and blocks off both the air entrance 31 and the air exit 33. Therefore, the air can only travel through the air passage comprising the air entrance 32, the chamber 26, and the air exit 34 to the air conduits l9 as illustrated by the small arrows following the air path in the Figure 1. The compressed motive fluid as thus directed through the air conduit I9 will, therefore, create a differential of air pressure with respect to the piston l6 and force the piston l6 toward the end of the tool cylinder 28 defined by the internal bore 27 of the valve 2|.

The piston 16 fits closely to the tool cylinder 28 along a portion of the length of the piston and, therefore, provides an upper corner 39 and a lower corner 43. As the upper corner 39 of the piston [6 passes the upper edge ofthe air It does not matter 4 exhaust 20, the air pressure in that portion of the cylinder 28 is compressed to a small extent, but more important, is no longer freely exhausted to atmosphere. Further, as the corner 40 of the piston I 6 passes the lower edge of the air exhaust 20, the air conduits H! are vented to atmosphere; therefore, the pressure resisting exhaust through the air conduits I9 is greatly reduced. Because of the reduction in resistance to the air flow through air conduit [9, and because of the concurrent increase of resistance to air flow from the cylinder 23 at the valve end, the differential of pressure previously existing in the position illustrated in Figure 1 will be reversed and consequently, the ring valve 35 will be quickly drawn tightly against the flat wall 30 at the bottom of the valve chamber 26. Thus, the fiow of air through the passage defined by the air entrance 32, the chamber 26, and the air exit 34 will be blocked and the air will be directed through the air entrance 3! in the cap 25, the chamber 26, and out through air exit 33 into the adjacent end of the tool cylinder 28. The consequent differential of air pressure upon the piston i6 will drive the piston 13 down toward the tool bit I! with great force.

As the upper corner 33 closes the exhaust 23 in the upward movement of the piston l6, or as the lower corner 40 closes the exhaust 23 in the downward movement of the piston IS, the motive fluid trapped in the respective ends of the tool cylinder v28 will be compressed considerably and, therefore, help to change over the pressure differential within the chamber 25 acting upon the ring valve 35, but the slight compression thus created is small in effecting the change as compared to the sudden venting of the air exits 33 and 34 to atmosphere.

In the Figure 11, the ring valve 35 is illustrated as having a rectangular cross-sectional area with a surface dimension to adequately cover the inlets and outlets of the valve 2%, but being free to move rapidly into contact with one or the other of the flat walls 23 and 33. It has been found, however, that the use of improper lubricants in the air stream will sometimes deposit a film on the fiat surfaces 29 and 33 which will tend to cause fiat surfaces 36 and 37 to adhere tightly to the flat surfaces 29 and 30. This resistance to separation is more than mere tackiness of the lubricant, but is the same principle as illustrated by the adherence of two perfectly fiat ground surfaces clinging together by air pressure differential. Therefore, it has been found that the ring valve 35 may preferably be Warped out of a. perfect plane form a slight amount in order to present a surface which does not exactly match the fiat surfaces 29 and 30. However, the ring valve 35 is resilient and, therefore, may be drawn into perfect sealing contact with surfaces 29 and by the pressure differential operating the valve. Thus, when the pressure differential reverses as previously described, the momentary equalization of air pressure during the transition of the air pressure will allow the resiliency of the ring valve 35 to snap to a warped shape and break the natural air seal which might otherwise cause the ring valve 35 to cling and delay the rapid reversal of air direction.

Although the invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and thatnumerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and the scope of the invention as hereinafter claimed.

What is claimed is:

1. An air tool comprising, a tool body having a cylindrical bore, said cylindrical bore havingafirst and a second end, and an intermediate portionbetween the ends, said tool body having an opening through the said intermediate portion of the bore providing an exhaust port, an annular valve body having an annular groove therein with a flat wall bottom, an annular valve cap havin a flat wall surface, the valve cap and valve body comprising a valve cage, a cap member threadably engaged on said first end of the tool body, said valve body and valve cap clampingly held together and in operative position at the first end of said tool body by said cap member, said valve cage having an internal bore, said cylindrical bore of the tool body and internal bore of the valve cage comprising a tool cylinder, the groove in the valve body defining an annular valve chamber therein having the fiat wall surface of the valve cap as a first fiat wall of the chamber, and the fiat wall bottom of the groove as a second fiat wall of the chamber, said valve cap having at least an opening through said first fiat wall for a first air entrance into said chamber, said valve cap having at least an opening through said first fiat wall for a first air exit from said chamber, said valve body having at least an opening through said fiat wall bottom for a second air entrance into said chamber, said valve body having at least an opening through said flat wall bottom for a second air exit from said chamber, an annular resilient valve ring in said annular valve chamber, said valve ring being warped untrue with respect to the flat walls of the chamber and being adapted to be flattened by fluid pressure into fiat sealing contact with a selected one of said first and second flat walls of the valve chamber, an air line conduit adapted to conduct air from said second exit to said second end of the cylinder, said first air exit opening into the first end of the tool cylinder, and a free piston in said tool cylinder providing a movable cylinder division whereby air may be alternately exhausted from one end of the cylinder and trapped in the other end.

2. An air tool comprising, a tool body having a cylindrical bore, said cylindrical bore having a first and a second end, and an intermediate portion between the ends, a piston in said cylindrical bore providing a movable cylinder division, said tool body having an exhaust port controlled by the piston, an annular valve body having an internal bore, a cap member on said first end of the tool body, said valve body clampingly held on the first end of the tool body by said cap, said annular valve body having an annular valve chamber therein, inlet passages leading from the opposite sides of the valve chamber to the ends of the tool cylinder, a supply passageway leading from a source to constantly supply pressure fluid to said valve chamber, an annular resilient valve ring in said annular valve chamber, said valve being warped untrue with respect to the sides of the valve chamber and being adapted to be flattened by fluid pressure into sealing contact with a selected side of said valve chamber and seal off the inlet passages leading therefrom.

3. An air tool comprising, a tool body having a cylindrical bore with a iree piston therein, an annular valve body directing pressure fluid to the ends of said bore, said valve body having oppositely disposed walls with inlet passageways through said walls to the ends of the cylinder, a ring valve plate in said valve body, said ring valve plate free to reciprocate between the oppositely disposed valve walls and alternately block passage of fluid through the inlet passageways in the walls, said ring valve plate operating in response to change in relative back pressure against exhaust from said valve and being warped untrue with respect to the oppositely disposed walls of the valve but resilient to conform to the walls by air pressure differential.

PAUL R. VAN SITTERT.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,068,711 Taylor July 2-9, 1913 1,361,431 Wilson Dec. '7, 1920 1,924,812 Shaff Aug. 29, 1933 2,040,842 Gartin May 19, 1936 FOREIGN PATENTS Number Country Date 166,122 Great Britain June 29, 1922 21,123 Australia Jan. 7, 1930 of 1929 686,729 France Apr. 15, 1930 

